A variety of types of light sensors are known which can be mounted on an integrated optical circuit in order to receive light from a waveguide integrated on the circuit. One example is a SiGe/Si multi-quantum well (MQW) structure arranged to form a photodetector which can be mounted on a silicon optical circuit to receive an optical signal directed thereto by a waveguide.
The present invention alms to provide a light sensor having advantages over such known light sensors.